Warsaw Pact

The Warsaw Pact was a collective defense treaty signed by the Soviet Union and seven of its communist puppet states on 14 May 1955. It consisted of the USSR, East Germany, Poland, Bulgaria, Czechoslovakia, Romania, Hungary, and Albania (which withdrew from the alliance in 1968), and it was the Eastern Bloc's counterpart to the Western Bloc's NATO. It ended with the end of the Cold War in 1991.

History
The Warsaw Pact was formed on 14 May 1955 as the military arm of Comecon, the Eastern Bloc's economic alliance. The Warsaw Pact was formed to guarantee that the communist states would defend each other in the case of an attack by the West, and it allowed for the Soviet Union to maintain control over military forces in Eastern Europe and Central Europe, where they had puppet states. In 1968, the Warsaw Pact carried out its largest military intervention after the Prague Spring uprising broke out in Czechoslovakia, with Alexander Dubcek's government being overthrown by the Soviets. The pact proved to be a military obstacle to the West's NATO alliance, and it helped to prevent a third world war from breaking out. However, the 1989 revolutions were able to overthrow several of the Warsaw Pact states, and the Warsaw Pact was dissolved on 1 July 1991 after the end of the Cold War.